Well, at some level, most of them. But which may be limiting your own energy is going to vary from person to person. Vitamin D is a common one, I take it too. For me, taking fish oil, zinc, and a B complex (with food, they make me nauseous on an empty stomach, and no mega-doses) are also helpful. So is proper hydration. For me, that means at least 100 oz of fluids a day, and I find it helpful if it has a splash of citrus or other juice in it - the little bit of sugar seems to matter, ditto for it being helpful for me to eat high water content fruits and vegetables.
When, how often, and how much at a time you eat matters too. Some people do well with small meals more often. I have more energy eating keto but have a hard time keeping to it. I also do better intermittent fasting (anywhere from 16:8 to OMAD) with my main meal in mid-afternoon or later with (usually) little to no refined carbs and refined oils, and I've been doing that for a couple of years.
You say you're constantly tired. Does it vary throughout the day? Is it worse at specific times, or times relative to meals, or in response to different types of activities? Timing food and hydration based on mental, physical, and emotional activity can matter a lot.
Beyond nutrition, lots of medications can cause drowsiness in some people (I have allergies and every antihistamine causes me serious mental and energy issues; the least bad for me is Allegra and even then I can only take it once or twice a week at most).
How is your air quality at home/work/wherever? Ambient noise levels? Light levels? (I find brighter indoor light helpful, but conversely, I found that being in the sun makes me tired, and started wearing a sun hat and darker sunglasses when spending a lot of time outside). These can have both physical and mental effects on energy.
Since you mentioned a healthy brain, keep in mind that it's also very easy for mental health to affect energy levels in ways you might not immediately notice. There are the well known ones like chronic stress, depression (it took me 10 years to realize I was depressed; I spent 5 of them thinking I had a sleep disorder, and was on modafinil for 4 of those), and so on, but also things that vary quite a lot from person to person. For example, I find strong emotions leave me feeling drained, even good ones.
And there are genetic factors: how are the rest of your family's energy levels? I grew up thinking it was normal to not be able to stay awake throughout a movie even when you're enjoying it and it's mid-day, or to fall asleep mid-conversation after a meal, because most of my immediate family has those issues like I do.
In addition to the 23andMe recommendation from ChristianKI, you might want to consider trying Viome, an at-home blood and gut microbiome panel. My wife did it (not for tiredness), and the recommendations were very specific, tried to be explanatory in a way that wouldn't overwhelm most people, and (with some analysis and research and background knowledge) pointed towards a single underlying cause.